If you stick around here for a while, you'll realize how silly it sounds to most of us that you ONLY have 2 products to do the same job...most of us have 8 or 10.
But seriously, yes, Z-6 is a quick detailer, Z-8 is a spray sealant, and OCW is a spray wax. So yes, technically Z-8 and OCW "do the same job", but they are very different products. Maybe sometimes you feel like a nut, sometimes you don't...and some days or some cars you might feel like Z-8, while other days or other cars you might feel like OCW.
Just out of curiosity, what did you think you were buying with these 3 products? Two QD's and one spray wax? Then you would still have had two products doing the same job.